Circuit interrupter



May 13, 1941.

s. s. GRADY 2,242,066

CIRCUIT INTERRUPTER Filed Feb. 2, 1939 2 Sheets-Shut 2 PZz-a. 1.5. z5 79V( 24 Inseln/fan JJ k Ins u/afZlZn ATTORNEYS Patented May 13, 1941 UNITED STATES PATENT OFFICE CIRCUIT INTEBRUPTER Stephen S. Grady, Clinton, N. C.

Application February 2, 1939, Serial No. 254,168

(Cl. 20G-88) 18 Claims.

This invention relates to new and useful improvements in circuit interrupters or breakers, and more particularly it pertains to that type of circuit breakers which function automatically to open or break an electric circuit when an overload condition exists therein.

While the invention has been herein illustrated in a circuit breaker of the so-called "panel type, it is to be understood that the invention is not limited to devices of this specific type and that it is equally adaptable to circuit breakers of other types.

It is the object of the invention to improve the construction of such devices, render them more simple and emcient in operation and this, without increasing materially, their cost of construction.

A feature of the invention resides in the provision of a novel form of interposer which is so constructed that, as it passes to or from position between a pair of electrical contacts either to break or establish an electrical circuit of which the contacts form a part, there will be substantially no arc produced as is true of so many devices of this nature.

It is another feature of the invention to provide both a new and novel means for operating the interposer, whereby the interposer may be moved automatically from a set position out of engagement with the contacts to a position beposition out of engagement therewith and to the position in which it is held for automatic operation, the interposer is operated by a manually operated means andit is a further feature of this invention, so to construct this manually operated means that it may, when the interposer is Vin that 'position in which it is set for automatic operation, be operated independently as an interposer to establish or break the circuit and this entirely independently of the automatically operated linterposer and without in any manner disturbing the set position of the automatically operated interposer.

From the foregoing, ,it will be obvious that the device employs in eiect, two interposers and it is further feature of this invention so to constructthese two interposers that one of them will be manually operated in its both directions of movement, while the other will be automatic in its movement from a set position to which it is moved by the manually operated interposer.

Still a further feature of the invention resides in a novel construction and arrangement of parts whereby a single means may be employed to perform the two functions of retaining the automatically operated interposer in its` set position and also for moving it from its set position to position between the contacts to separate them and thereby interrupt or break the circuit of which the contacts are a part.

Still a further feature of the invention resides in a novel construction and arrangement of parts whereby the automatically operating interposer may be released, either by a thermal device, or by an electro responsive magnetic device which operate independently of each other.

A still further feature of the invention resides in a novel construction and arrangement of contacts and a novel manner of mounting. or supporting them for operation.

Other features and objects of the invention will become apparent as the nature of the invention is better understood and reference will therefore be had to the following specification and claims and to the accompanying drawings wherein the invention is illustrated in a preferred form.

In the drawings:

Figure 1 is a top edge view in elevation, illustrating a circuit interrupter or breaker constructed in accordance with the present invention, the cover plate of the housing being removed,

Figure 2 is a longitudinal sectional view taken substantially on the line 2-2 of Figure 1, the automatically operated interposer being illustrated in the lposition which it occupies when it is set for automatic operation,

Figure 3 is a view similar to Figure 2, the automatlcally operated interposer being illustrated in position between the contacts to which position it has been moved by an automatic operation, the manually operated interposer being out of engaging relation with the contacts,

Figure 4 is a detail fragmentary sectional viewl Figure 6 is a detail edge view in elevation of the manually operated interposer,

Figure 7 is a detail side view in elevation of the manually operated interposer,

Figure 8 is a detail bottom plan view of the manually operated interposer,

. Figure 9 is a detail edge view in elevation of the automatically operated interposer,

Figure 10 is a detail side view in elevation of the automatically operated interposer,

Figure 11 is a bottom plan view of the automatically operated interposer,

Figure 12 is a detail plan view of a shield element employed in connection with one of the contact elements, and;

Figure 13 is a schematic view illustrating certain of the steps and relative positions of the manually operated interposer and the automatically operated interposer and the contacts, as the automatically operated interposer is moved from between the contacts to the position in which it is set for automatic operation.

Referring to the drawings by reference characters, designates a suitable housing for the circuit breaker. This housing is constructed from any suitable material 4which is a non-conductor of electricity and in the present illustration of the invention, it consists of a relatively t'-"an block 2| of material so shaped as to ac- Lgimodate and mount the several elements of thdevice. Side plates 22, secured in position by screws or the like 23 and a cover plate 24 secured in position by screws or the like 25 serve to complete the housing and enclose the operating parts of the device.

The reference character 26 designates an L- shaped member having two legs 21 and 28. The leg 21 of this member extends along one of the side pla/tes 25 and preferably in contact therewith and this leg 21 constitutes one of a. pair of contacts which are included in the electrical circuit which the device is adapted to control. This L-shaped member 26 may be secured in position by a bolt or the like 29, which extends through the block 2| and its free end is adapted for ,threaded engagement with a plate 36 which carries a. screw 3| which screw constitutes a binding post.

The binding post 3| is preferably at one end of the housing as shown and at the opposite side end of the housing there is another binding post 33 preferably in the form of a bolt which has threaded engagement with the block and which also serves to hold in position, a plate 34 of suitable conducting material. The binding posts 3| and 33 serve to electrically connect the device in an electrical circuit which it is intended to control and-this complete circuit will now be described. .:2,

The reference character 35 designates a terminal screw or bolt which, when screwed home, has electrical contact with the plate 34 heretofore By reference to Figure 13, it will be noted that the contact is looped to provide a pair of curved cam faces 46 and 41 and it is this looped portion which has engagement with the contact 21 to complete through the device, one leg of an. electrical circuit between the two terminals 3| and 33. It is to be understood that the exension 44 of the coil 42'and the contact element 45 are of such construction and arrangement that at all times, the contact 45 is urged in the direction of the contact 21, and that, in the present illustration of the device, the contact 45 will move into electrical engagement with the contact 21 except when prevented from so doing by means and in a manner to be described hereinafter.

The reference character 50 designates an armature for the solenoid coil 42. This armature is loosely slidable longitudinally of the coil 42 and is provided on each end with means in the form of a shoulder 5| to prevent its accidental displacement from within the coil. 'I'he armature 5|! is moved forwardly, or towards the left in the drawings by the presence in the coil of electrical current in excess. of that for which the coil is designed and is moved to its retracted position in which it is shown in Figure 2, by means which will be hereinafter described.

In Figure 12 there is shown a shield for the contact 21 which shield consists of a relatively thin sheet 52 of non-conducting material. The shield is cut out as at 53 to receive the contact 21 and is formed from a, sheet of material which is of greater thickness than the material from which said contact 21 is formed. This construction provides, in effect, a recess in which the contact 21 rests with that face or portion thereof which is engaged by the contact 45, slightly below the exposed face of the shield 52 as illustrated in Figure 13.

Extending transversely of the housing near that edge which is closed by the vcover plate 24, there is a shaft 60, carried by this shaft 66 and having free pivotal movement thereon, there is ward edge, it is provided with a notch 64 and a knife edge 65. This knife edge is provided to facilitate movement of the interposer between the mentioned and leading from and having electrical contact with the terminal 35, there is an electrical conductor 36. This electrical conductor 36 is preferably of the exible type and is electrically connected as at 31 to a thermal responsive conductor 38 preferably in the form of a suitable length of bi-metal. This conductor 38 has electrical connection with a screw or bolt 46 which also serves to secure it to a suitable support herein illustrated as an arm 4| which projects inwardly of the housing.

contacts and thereby preventA arcing between the contacts 21 and 45 as the interposer passes to and from position therebetween. The interposer is also provided with a rearwardly extendfing projection 66, which, as illustrated in Figure The reference character 42 designates a solenoid coil the end 43 of which has electrical connectin with the screw or bolt 46. The opposite end of the coil 42 is extended as indicated by the reference character 44 and upon its free end it carries a contact 45, which, together with the leg 21 of the L-shaped member 26, forms the pair of contacts heretofore referred to.

2, underlies the free end of the bi-metal cony ure 4. The opposite end of the spring 69 carries a looped link 1| which straddles the curved upper edge of the head portion 62 of the interposer and has engagement in the notch 64.

' ByrefcrencetoFigure10,itwillbenctedthat the notch 54 is slightly below the mounting opening 52 of the interposer which construction provides an over-center pull by the spring 55 which serves to hold the interposer in its set position and also to move it to its position between the contacts when it is tripped or released by movement of the interposer to such position that the pull of the spring is exerted above the pivotal point of the interposer. In other words, the spring will serve to hold #the interposer in its set position in which it is illustrated in Figure 2 and will also serve to move it to position between the contacts in which position it is shown in Figure 3, the latter action taking place upon a slight pivotal movement of the interposer in a clockwise direction in the drawings, when it is in the set position shown in Figure 2.

The interposer is moved from its tripped position to its set position by manually operated means designated 15 in the drawings, which also, functions as aninterposer for entrance to posi.. tion between the contacts 21 and 45 to separate them.

By reference to Figures 6 through 8, this manually operated means will be seen to comprise a main body portion 15 having an opening 11 therethrough by which it may be pivotally mounted upon the shaft 4l heretofore referred to. Ex-

tending in one direction from the body portion 15 there is an operating member 1l, which, when the member is mounted upon the shaft 50, projects through an elongated opening 15 in the cover plate 24. Extending from the opposite side of the body portion 10, there is an arm 19 which, when the member is mounted upon the shaft 55, is adapted to move the interposer 6i from position between the contacts 21 and 45. This arm in its operation of the interposer also between the contacts 21 and 45 and serves to maintain them separated if desired. after the interposer 5i has been moved out of engagement therewith. The arm 12 has a knife edge 5l so constructed and arranged as to facilitate its movement to position between the contacts as it passes to and from its position between the same.

As heretofore stated, the construction of the extension 44 of the coil 42 is such that the contact 45 is normally urgedinto engagement with the contact 21 and this tendency is augmented by additional means which will now be described.

Mounted for pivotal movement upon the shaft 50. there is a resilient member 55 which is of elongated rectangular form and of suiiicient length to extend over the contact 45. A pin or the like 55 `which is carried by the interposer 5i,

`passes through an opening 81 in the resilient member I5 so that as the interposer is rocked about the shaft 55, the resilient member 85 will also pivot about the shaft II and will be carried with the interposer 5 i.

The relation of the resilient member 55 to the interposer 5i is such that as the interposer is moved from its tripped position of Figure 3, to its set position of Figure 2 of the drawings, the resilient member will ride the inclined portion of the contact and exert a pressure thereon to aid in moving it into engagement with the contact 21. In the tripped position of the interposer, the resilient member moves to a position where it does not engage the contact 45 and therefore exerts no pressure thereon.

5| in position between the contacts 21 and 4l, separating them and serving to interrupt the circuit. This position of the parts is also illustrated in the first stage of Figure 13.

To set the switch, the manually operated lever 15 is moved in a counterclockwise direction as in Figure 3. This action causes engagement of the arm 19 thereof with the adjacent edge of the interposer 5i, moving the interposer lfrom position between the contacts 21 and 45, this position of the parts being vshown in the second stage of Figure 13. At this time, the resilient member 55 has ridden up the inclined portion Il of the contact 45 and is exerting pressure upon said contact. As the movement of the manually operated lever 15 progresses, the interposer is moved entirely beyond the contacts 21 and 45,

with the arm 19 of said lever interposed between the contacts 21 and 45 which position of the parts is illustrated in the third stage of Figure 13. With the parts in this position, the manually operated lever 15 is moved in a clockwise direction whereupon it moves from position between the contacts 21 and 45 and permits the contact 45, under the influence of the resiliency of the extension 44 of the coil 42 and the resiliency of the resilient member 55. to engage the contact 21 in which position the parts are shown in the fourth stage of Figure 13. A suitable stop 35 is provided to limit the rearward movement of the interposer 6i.

The foregoing is the set position of the interposer and is shown in Figure 2. By reference to said Figure 2 it will be noted that the bi-metal member 38 is resting upon the rearwardly extending projection 55 of the interposer with the interposer free of the contacts 21 and 45 while the arm 19 of the manually operated lever is in its extreme left position out of engagement with either the contacts 21 and 45 or the interposer 5|.

With the parts in this position, the manually operated lever 15 is free to move to and from position between the contacts 21 and 45 independently of the interposer 5i and therefore, in itself, constitutes a manually operated interposer for interrupting the circuit independent of the interposer 5i.

The device is set for automatic operation with the parts in the position shown in Figure 2 and with the parts in this position, the interposer may be tripped or released to be moved to position between the contacts 21 and 45 by the spring 55. either by the bi-metal element 38 or the core 55 of the solenoid.

For example, should the circuit interrupter be connected between a constant voltage supply circuit and a load circuit and should the impedance of the load circuit remain at an abnormally low value, for sufliclent period of time, then the resuiting increased current flow would produce an increasing temperature in the bi-metai element causing it to bendf Downward deflection of its free end will exert sumcient pressure upon the projection 55 of the interposer to move the same to a point where the over-center spring 55 will move it to positionbetween-the contacts 21 and 45 to separate the same and interrupt the circuit.

On the other hand, should a condition occur which would cause a flow of current in excess of the maximum normal current, the coil 42 of the solenoid will be excited suillciently, instantly -to move the armature -55 thereof forwardly, or to the left in Figure 2, to the dotted line position shown in Figure 3 and will impart a blow to the interposer of suilicient force to move it to thepoint where the over-center spring 6,9 will eiect its movement to position between the contacts 21 and 45 to separate the same and interrupt the circuit.

By reference to Figure 13,. it will be noted that as the interposer 6l moves from its set position to its tripped position, the resilient member 85 rides down the inclined portion 90 of the contact 45 and thus progressively relieves the tension exerted uponthe contact member 45 by the resilient member 85, thereby progressively reducing the resistance offered to the movement of the interposer toits position between the contacts 21 and 45.

To again reset the interposer 6l for automatic operation, it is only necessary to rock the manually operated lever about the shaft 60 in an anticlockwise direction as heretofore described. On the other hand, should it be desired to interrupt the circuit and at the same time maintain the interposer 6| in its set position, it is only necessary to move the manually operated lever 15 in an anti-clock-wise direction until its arm 19 passes between the contacts 21 and 45 suiciently to separate them,

thereby interrupting the circuit and maintaining the same interrupted so long as the arm 19 is left in position between the contacts.

From the foregoing then, it will be apparent that the present invention provides both an automatically operated interposer for movement between a pair of contacts and a manually operated interposer which is capable of operation independently of the automatically operated interposer and which also serves as means for moving the automatically operated interposer ment by its operating means, to position between z the contacts.

2. In a circuit interrupter, a pairof contacts having normal engagement with each other, an interposer movable tov position between the contacts to separate the same, manually operated means for moving the interposer from between the contacts to permit of their engagement with each other, a single means comprising a spring for holding said interposer in said last mentioned position and for operating it to position between the contacts, and a pluralityof current responsive .means operable independently of each other for releasing the interposer for movement by its operating means, to position 4between the contacts.

3. Ina circuit interrupter, a pair of contacts having normal engagement with each other, an

is moved from position therebetween and being subsequently movable from between the contacts to permit of theirl engagement with each other.

4. In a circuit interrupter, a pair of contacts having normal engagement with each other, an interposer movable to position between the contact to separate the same, means for moving the interposer to position between the contacts, and independent means for moving the interposer from position between the contacts, said last mentioned means entering between the contacts to maintain them separated when the interposer is moved from position therebetween and being subsequently movable at will from or to a self maintained position between the contacts without disturbing the position of the interposer when it is out of engagement with the contacts.

5, In a circuit interrupter, a pair of contacts having normal engagement with each other, an interposer movable to position between the contacts to separate the same, means for moving the interposer to position between the contacts, independent means for moving the interposer from position between the contacts, said last mentioned means entering between the contacts to maintain them separated when the interposer is moved from position therebetween and being subsequently movable from between the contacts to permit of their engagement with each other, and releasable means for retaining said interposer in position where it does not engage the contacts, said releasable means also serving to move the interposer to position between the contacts.

6. In a circuit interrupter, a pair of contacts having normal engagement with each other, an interposer movable to position between the contacts to separate the same, means for moving the interposer to position between the contacts, independent manually operated means for moving the interposer from position between the contacts, said manually operated means entering between the contacts to maintain them separated when the interposer is moved from position therebetween and being subsequently movable at will from or to position between the contacts without disturbing the position of the interposer when it is out of engagement with the contacts, and means for retaining said manually operated means against accidental displacement relative to the contacts when it is in position therebetween.

7. In a. circuit interrupter, a pair of contacts having normal engagement with each other, an interposer movable to position between the contacts to separate the same, means for moving the interposer to position between the contacts, independent manually operated means for moving the interposer from position between the contacts, said manually operated means entering between the contacts to maintain them separated when the interposer is moved from position thereibetween and being subsequently movable at will from or to position between the contacts without interposer movable to position between the contacts to separate the same, means for moving the interposer to lposition between the contacts,

disturbing the position of the interposer when it is out of engagement with the contacts, and means for exerting a yielding pressure upon one of said contacts to releasably hold the manually operated means against accidental displacement from its position between the contacts.

8. In a circuit interrupter, a xed contact, a movable contact, means for exerting pressure upon the movable contact to cause it normally to engage the fixed contact, an interposer movable to position between the contacts against the terposer is moved to its position between the conengage the fixed contact, an interposer movable to position between the contacts against the pressure exerted upon the movable contact, to separate the contacts and to maintain them separated, said interposer being movable from its position between the contacts to permit of the movable contact engaging the fixed contact, and means whereby-the pressure upon the movable contact and the interposer is progressively relieved as the interposer is moved to its position between the contacts.

10. In a circuit interrupter, a housing of insulating material one oi' the walls of said housing having a plane inner face with a recess therein, a fixed electrical contact element mounted in said recess, the recess being deeper than the thickness of the contact member whereby the side walls of the recess extend beyond the plane of the contact face oi' the said contact element, a second contact element normally biased towards engagement with said fixed contact element, and an interposer movable along said plane inner face to position between the contacts to separate them from each other.

11. In a circuit interrupter, a housing of insulating material one of the walls of said housing having a plane inner face with a recess therein,

a ilxed electrical contact element mounted in said recess, the recess being deeper than the thickness oi' the contact member whereby the side walls of the recess extend beyond the plane of the contact element, and an interposer movable along said plane inner face to position between the contacts to separate them from each other, said interposer serving completely to close the recess in which the nxed contact element is mounted when the interposer is in position between the contact elements.`

12. In a circuit interrupter, a fixed contact, a movable contact, means biasing said movable contact toward engagement with said nxed contact,

'an interposer movable to position between the' contacts to eirect a separation oi' the contacts,

' said interposer comprising a member of insulating material having an entering edge eiTectve substantially to prevent an electrical arc between the contacts, and means independent of said interposer for eectlng separation oi' the contacts.

13. In a circuit interrupter, a iixed contact, a movable contact, means biasing the movable contact towards engagement with the fixed contact, an interposer of insulating material movable to position between the contacts to separate them, means for moving the interposer from position between the contacts, said means comprising a plvotally mounted member of insulating material for engagement with the interposer and movable to position between the contacts as the interposer is moved out of engagement with the contacts and being subsequently movable to position from between the contacts to permit o! engagement of the contacts, and means operable independently of the pivoted member for moving the interposer again between the contacts.

14. In a circuit interrupter, a housing, a stationary contact, a movable contact adapted for engagement with the stationary contact, means tending to move the movable contact into engagement with the stationary contact, an interposer plvotally mounted in the housing and movable to position between the contacts to separate them and to a position from between said contacts to permit of their engagement with each other, manually operable means for moving said interposer from between the contacts, and a single means for holding said interposer in said last mentioned position and for moving it to position between the contacts.

l5. In a circuit interrupter, a housing, a stationary contact, a movable contact adapted for engagement with the stationary contact, means tending to move the movable contact into engagement with the stationary contact, an interposer plvotally mounted in the housing and movable to position between the contacts to separate them and to a position from between said contacts to permit of their engagement with each other, manually operable means for moving said interposer from between the contacts, and a single means for holding said interposer in said last mentioned position ,and for moving it to position between the contacts, said last mentioned means comprising a spring connected at one end to the housing and at its other end to said interposer at a point whereby it passes to opposite sides of the pivotal point of the interposer in its pivotal movement.

16. In a circuit interrupter, a stationary contact, a movable contact, automatic current responsive means for causing separation of said contacts comprising an element oi' magnetic material and a coil oi' conducting material traversed by current owing through said contacts for producing a magnetic field for causing movement of said element, a conducting support for said movable contact, said coil and said support formed from a continuous elongated conductor.

17. In a circuit interrupter in combination, a pair oi' contacts having normal engagement with each other, an interposer movable to position between the contacts to separate the same, manually operated means for moving the interposer from between the contacts to permit oi' their engagement with each other, means comprising an over-center spring for holding said interposer in said last mentioned position and for operating it to position between the contacts. and thermal responsive means for releasing the interposer for movement by its operating means, to position between the contacts.

18. In a circuit interrupter in combination, a pair of contacts having normal engagement with each other, an interposer movable to position between the contacts to separate the same, manually operated means for moving the interposer from between the contacts to permit of their engagement with each other, a single means for both holding said interposer in said last mentioned position and for operating it to position between the contacts, and magnetic means for releasing the interposer for movement by its operating means, to position between the contacts.

STEPHEN S. GRADY. 

